ARDS (Acute respiratory distress syndrome)
Acute respiratory distress syndrome or A.R.D.S. is an emergency and life-threatening condition where the lungs can't provide the body's vital organs with enough oxygen.
It occurs when fluid builds up in the tiny, elastic air sacs called alveoli in the lungs. The fluid keeps the lungs from filling with enough air, which means less oxygen reaches the bloodstream. This deprives the organs of the oxygen they need to function.
It's usually a complication of a serious existing health condition. Most people have therefore already been admitted to hospital by the time they develop A.R,D.S.
Many people who develop this disease don't survive. The risk of death increases with age and severity of illness. Of the people who do survive ARDS, some recover completely while others experience lasting damage to their lungs.
Symptoms of acute respiratory distress syndrome
The signs and symptoms of ARDS can vary in intensity, depending on its cause and severity, as well as the presence of underlying heart or lung disease.
The symptoms of ARDS typically appear between one to three days after the injury or trauma.
Common symptoms and signs of ARDS include:
Severe shortness of breath
Laboured and unusually rapid breathing
Low blood pressure
Confusion and extreme tiredness
Discoloured skin or nails
Dry, hacking cough
Fever
Headaches
Fast pulse rate
ARDS usually follows a major illness or injury, and most people who are affected are already hospitalized.
What causes acute respiratory distress syndrome?
ARDS occurs when the lungs become severely inflamed due to an infection or injury. The inflammation causes fluid from nearby blood vessels to leak into the tiny air sacs in your lungs, making breathing increasingly difficult. These air sacs are where oxygen enters and carbon dioxide is removed from your blood. When these air sacs fill with fluid, less oxygen gets to your blood.
The most common underlying causes of ARDS include:
Sepsis. The most common cause of ARDS is sepsis, a serious and widespread infection of the bloodstream.
Inhalation of harmful substances. Breathing high concentrations of smoke or chemical fumes can result in ARDS, as can inhaling (aspirating) vomit or near-drowning episodes.
Severe pneumonia. Severe cases of pneumonia usually affect all five lobes of the lungs.
Head, chest or other major injury. Accidents, such as falls or car crashes, can directly damage the lungs or the portion of the brain that controls breathing.
An adverse reaction to a blood transfusion
Overdosing on sedatives or tricyclic antidepressants
Others. Pancreatitis (inflammation of the pancreas), massive blood transfusions and burns.
Depending on the amount of oxygen in the blood and during breathing, the severity of ARDS is classified as:
Mild
Moderate
Severe
What Are Risk Factors?
While it is not clear who will develop ARDS, there are a few factors that may increase the risk for ARDS. These factors include:
A history of cigarette smoking
Oxygen use for a pre-existing lung condition
Recent high-risk surgery
Obesity
Low protein in the blood
Alcohol abuse
Recent chemotherapy
Complications of ARDS
If you have ARDS, you can develop other medical problems while in the hospital. The most common problems are:
Blood clots. Lying still in the hospital while you're on a ventilator can increase your risk of developing blood clots, particularly in the deep veins in your legs. If a clot forms in your leg, a portion of it can break off and travel to one or both of your lungs (pulmonary embolism) — where it blocks blood flow.
Collapsed lung (pneumothorax). In most ARDS cases, a breathing machine called a ventilator is used to increase oxygen in the body and force fluid out of the lungs. However, the pressure and air volume of the ventilator can force gas to go through a small hole in the very outside of a lung and cause that lung to collapse.
Infections. Because the ventilator is attached directly to a tube inserted in your windpipe, this makes it much easier for germs to infect and further injure your lungs.
Scarring (pulmonary fibrosis). Scarring and thickening of the tissue between the air sacs can occur within a few weeks of the onset of ARDS. This stiffens your lungs, making it even more difficult for oxygen to flow from the air sacs into your bloodstream.
Thanks to improved treatments, more people are surviving ARDS. However, many survivors end up with potentially serious and sometimes lasting effects:
Breathing problems. Many people with ARDS recover most of their lung function within several months to two years, but others may have breathing problems for the rest of their lives. Even people who do well usually have shortness of breath and fatigue and may need supplemental oxygen at home for a few months.
Depression. Most ARDS survivors also report going through a period of depression, which is treatable.
Problems with memory and thinking clearly. Sedatives and low levels of oxygen in the blood can lead to memory loss and cognitive problems after ARDS. In some cases, the effects may lessen over time, but in others, the damage may be permanent.
Tiredness and muscle weakness. Being in the hospital and on a ventilator can cause your muscles to weaken. You also may feel very tired following treatment.
Diagnosing acute respiratory distress syndrome
ARDS is a medical emergency, and an early diagnosis may help them survive the condition.
There's no specific test to diagnose ARDS. A full assessment is needed to identify the underlying cause and rule out other conditions.
The doctor may take a blood pressure reading, perform a physical exam, and recommend any of the following tests:
Blood tests: to measure the amount of oxygen in the blood and check for an infection.
Pulse oximetry test: where a sensor attached to the fingertip, ear or toe is used to measure how much oxygen the blood is absorbing
Chest X-ray. A chest X-ray can reveal which parts of your lungs and how much of the lungs have fluid in them and whether your heart is enlarged.
Computerized tomography (CT). A CT scan combines X-ray images taken from many different directions into cross-sectional views of internal organs. CT scans can provide detailed information about the structures within the heart and lungs.
Electrocardiogram: This painless test tracks the electrical activity in your heart. It involves attaching several wired sensors to your body.
Echocardiogram: A sonogram of the heart, this test can reveal problems with the structures and the function of your heart.
Bronchoscopy: an airway examination
Lung biopsy: A lung biopsy can also be conducted to rule out other lung diseases. However, this is rarely done.
Low blood pressure and low blood oxygen can be signs of ARDS. The doctor may rely on an electrocardiogram and echocardiogram to rule out a heart condition. If a chest X-ray or CT scan then reveals fluid-filled air sacs in the lungs, a diagnosis for ARDS is confirmed.
Treating acute respiratory distress syndrome
ARDS often needs to be treated in an intensive care unit.
The first goal in treating ARDS is to improve the levels of oxygen in your blood. Without oxygen, your organs can't function properly.
Treatment may include:
Breathing support (Oxygen)
The primary goal of ARDS treatment is to ensure a person has enough oxygen to prevent organ failure. A doctor may administer oxygen by mask. A mechanical ventilation machine can also be used to force air into the lungs and reduce fluid in the air sacs.
Management of fluids
Management of fluid intake is another ARDS treatment strategy. This can help ensure an adequate fluid balance. Too much fluid in the body can lead to fluid buildup in the lungs. However, too little fluid can cause the organs and heart to become strained.
Prone positioning
Hospitalized patients are typically in bed on their backs. However, lying face down (prone) may help improve oxygen levels in the blood and increase survival in patients with ARDS. This can be a very complicated task that takes an entire team to accomplish, and some patients may be too sick for this treatment. There are specialized beds designed to help position patients in the intensive care unit face down and, although they are convenient, they are not absolutely necessary for this therapy.
Medication
People with ARDS are often given medication to deal with side effects. These include the following types of medications:
Pain medication to relieve discomfort
Antibiotics to treat an infection
Blood thinners to keep clots from forming in the lungs or legs
Pulmonary rehabilitation
People recovering from ARDS may need pulmonary rehabilitation. This is a way to strengthen the respiratory system and increase lung capacity. Such programs can include exercise training, lifestyle classes, and support teams to aid in recovery from ARDS.
Outlook
ARDS is a serious disease that can be frightening for patients and families to endure. The outcomes tend to be better in younger patients, trauma patients and when ARDS is caused by blood transfusions. Most people will not die of the severely low oxygen levels in the blood associated with ARDS. However, the chance of dying increases dramatically if other organs begin to fail. This could include liver failure, kidney failure or severely decreased blood pressure.
